U.S. patent number 10,590,556 [Application Number 15/752,625] was granted by the patent office on 2020-03-17 for copper electroplating baths containing compounds of reaction products of amines and quinones.
This patent grant is currently assigned to Rohm and Haas Electronic Materials LLC. The grantee listed for this patent is Dow Global Technologies LLC, Rohm and Haas Electronic Materials LLC. Invention is credited to Chen Chen, Lingli Duan, Weijing Lu, Zukhra Niazimbetova, Maria Rzeznik.
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United States Patent |
10,590,556 |
Lu , et al. |
March 17, 2020 |
Copper electroplating baths containing compounds of reaction
products of amines and quinones
Abstract
A polymer composed of a reaction product of an amine and a
quinone. The quinone is a Michael addition receptor. The polymer
may be an additive for a copper electroplating bath. The polymer
may function as a leveler and enable the copper electroplating bath
to have high throwing power and provide copper deposits with
reduced nodules.
Inventors: |
Lu; Weijing (Fanling,
HK), Duan; Lingli (Pudong District, CN),
Niazimbetova; Zukhra (Marlborough, MA), Chen; Chen
(Pudong District, CN), Rzeznik; Maria (Marlborough,
MA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC
Rohm and Haas Electronic Materials LLC |
Midland
Marlborough |
MI
MA |
US
US |
|
|
Assignee: |
Rohm and Haas Electronic Materials
LLC (Marlborough, MA)
|
Family
ID: |
58487165 |
Appl.
No.: |
15/752,625 |
Filed: |
October 8, 2015 |
PCT
Filed: |
October 08, 2015 |
PCT No.: |
PCT/CN2015/091432 |
371(c)(1),(2),(4) Date: |
February 14, 2018 |
PCT
Pub. No.: |
WO2017/059563 |
PCT
Pub. Date: |
April 13, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180237930 A1 |
Aug 23, 2018 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G
73/024 (20130101); C25D 3/58 (20130101); C25D
3/56 (20130101); C25D 3/38 (20130101); H01L
21/2885 (20130101); H01L 21/76879 (20130101); H05K
3/424 (20130101); H05K 2203/0723 (20130101); C23C
18/1653 (20130101); C25D 7/123 (20130101) |
Current International
Class: |
C25D
3/38 (20060101); C25D 3/56 (20060101); C08G
73/02 (20060101); C25D 3/58 (20060101); H01L
21/288 (20060101); H01L 21/768 (20060101); H05K
3/42 (20060101); C25D 7/12 (20060101); C23C
18/16 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
104762643 |
|
Dec 2014 |
|
CN |
|
4941500 |
|
Apr 1974 |
|
JP |
|
Other References
CN104762643, 2014, Wang Jing, Derwent Abstract. cited by examiner
.
Search report for corresponding Europe Application No. 15 90 5661
dated Mar. 6, 2019. cited by applicant .
Machocho, et al, "Reaction of benzoquinones and naphthoquinones
with 1,8-diamino-3,6-dioxanonane and with
1,11-diamino-3,6,9-trioxaundecane", Tetrahedron Letters, Jul. 14,
2003, pp. 5531-5534, vol. 44, No. 29. cited by applicant .
Nithianandam, et al, "Quinone-amine polymers. V. Syntheses and
solubilities of several diamine-p-benzoquinone oligomers (PAQ)",
Journal of Applied Polymer Science, Jun. 5, 1991, pp. 2893-2897,
vol. 42, No. 11. cited by applicant .
Search report for corresponding Europe Application No. 15 90 5661
dated Apr. 8, 2019. cited by applicant .
Search report for corresponding China Application No.
201580083216.1 dated Oct. 25, 2019. cited by applicant.
|
Primary Examiner: Brooks; Clinton A
Attorney, Agent or Firm: Piskorski; John J.
Claims
What is claimed is:
1. An electroplating bath comprising one or more sources of copper
ions, one or more accelerators, one or more suppressors, one or
more electrolytes and one or more compounds comprising a reaction
product of an amine and a quinone wherein the amine has a formula:
##STR00015## where R' is hydrogen; and R comprises
H.sub.2N(CH.sub.2).sub.m--, HO--(CH.sub.2).sub.m--,
Q-(CH.sub.2).sub.m--, a moiety having a structure: ##STR00016## a
moiety having a structure: ##STR00017## or a moiety having a
structure: ##STR00018## where R.sub.1-R.sub.14 are independently
chosen from hydrogen and (C.sub.1-C.sub.3)alkyl; m is an integer
from 2-12, n is an integer from 2-10, p is an integer from 1-10, q
is an integer from 2-10 and r, s and t are numbers from 1 to 10;
and Q is a 5-6 membered heterocyclic ring having one or two
nitrogen atoms in the ring or Q is a benzene sulfonamide
moiety.
2. The electroplating bath of claim 1, wherein the amine has the
formula: ##STR00019## wherein R' is hydrogen and R is the moiety:
##STR00020## wherein R.sub.1-R.sub.6 are hydrogen, n is an integer
from 2-5 and p is an integer from 1-5.
3. The electroplating bath of claim 1, wherein the amine has a
formula: ##STR00021##
4. The electroplating bath of claim 1, wherein the quinone has a
formula: ##STR00022## where R.sub.15, R.sub.16, R.sub.17 and
R.sub.18 are independently chosen from hydrogen, hydroxyl, linear
or branched hydroxy(C.sub.1-C.sub.10)alkyl halogen, linear or
branched (C.sub.1-C.sub.10)alkyl and linear or branched
amino(C.sub.1-C.sub.10)alkyl.
5. The electroplating bath of claim 1, wherein the quinone has a
formula: ##STR00023## where R.sub.19 and R.sub.20 are independently
chosen from hydrogen, hydroxyl, linear or branched
hydroxy(C.sub.1-C.sub.10)alkyl halogen, linear or branched
(C.sub.1-C.sub.10)alkyl and linear or branched
amino(C.sub.1-C.sub.10)alkyl, and R.sub.21, R.sub.22, R.sub.23 and
R.sub.24 are independently chosen from hydrogen, hydroxyl, linear
or branched hydroxy(C.sub.1-C.sub.10)alkyl halogen, linear or
branched (C.sub.1-C.sub.10)alkyl and linear or branched
amino(C.sub.1-C.sub.10)alkyl.
6. The electroplating bath of claim 1, further comprising one or
more sources of tin ions.
7. A method of electroplating comprising: a) providing a substrate;
b) immersing the substrate in the electroplating bath of claim 1;
c) applying a current to the substrate and the electroplating bath;
and d) electroplating copper on the substrate.
8. The method of claim 7, wherein the electroplating bath of claim
1 further comprises one or more sources of tin ions.
9. The method of claim 7, wherein the substrate comprises a
plurality of one or more of through-holes and blind vias.
Description
FIELD OF THE INVENTION
The present invention is directed copper electroplating baths
containing compounds of reaction products of amines and quinones as
Michael addition receptors. More specifically, the present
invention is directed to copper electroplating baths containing
compounds of reaction products of amines and quinones as Michael
addition receptors which have high throwing power and copper
deposits with reduced nodules.
BACKGROUND OF THE INVENTION
Methods for electroplating articles with metal coatings generally
involve passing a current between two electrodes in a plating
solution where one of the electrodes is the article to be plated. A
typical acid copper electroplating solution includes dissolved
copper, usually copper sulfate, an acid electrolyte such as
sulfuric acid in an amount sufficient to impart conductivity to the
bath, a source of halide, and proprietary additives to improve the
uniformity of the plating and the quality of the metal deposit.
Such additives include levelers, accelerators and suppressors,
among others.
Electrolytic copper plating solutions are used in a variety of
industrial applications, such as decorative and anticorrosion
coatings, as well as in the electronics industry, particularly for
the fabrication of printed circuit boards and semiconductors. For
circuit board fabrication, typically, copper is electroplated over
selected portions of the surface of a printed circuit board, into
blind vias and trenches and on the walls of through-holes passing
between the surfaces of the circuit board base material. The
exposed surfaces of blind vias, trenches and through-holes, i.e.,
the walls and the floor, are first made conductive, such as by
electroless metallization, before copper is electroplated on
surfaces of these apertures. Plated through-holes provide a
conductive pathway from one board surface to the other. Vias and
trenches provide conductive pathways between circuit board inner
layers. For semiconductor fabrication, copper is electroplated over
a surface of a wafer containing a variety of features such as vias,
trenches or combinations thereof. The vias and trenches are
metallized to provide conductivity between various layers of the
semiconductor device.
It is well known in certain areas of plating, such as in
electroplating of printed circuit boards ("PCBs"), that the use of
levelers in the electroplating bath can be crucial in achieving a
uniform metal deposit on a substrate surface. Electroplating a
substrate having irregular topography can pose difficulties. During
electroplating a voltage drop typically occurs within apertures in
a surface, which can result in an uneven metal deposit between the
surface and the apertures. Electroplating irregularities are
exacerbated where the voltage drop is relatively extreme, that is,
where the apertures are narrow and tall. Consequently, depositing a
metal layer of substantially uniform thickness is frequently a
challenging step in the manufacture of electronic devices. Leveling
agents are often used in copper plating baths to provide
substantially uniform, or level, copper layers in electronic
devices.
The trend of portability combined with increased functionality of
electronic devices has driven the miniaturization of PCBs.
Conventional multilayer PCBs with through-hole interconnects are
not always a practical solution. Alternative approaches for high
density interconnects have been developed, such as sequential build
up technologies, which utilize blind vias. One of the objectives in
processes that use blind vias is the maximizing of via filling
while minimizing thickness variation in the copper deposit between
the vias and the substrate surface. This is particularly
challenging when the PCB contains both through-holes and blind
vias.
Leveling agents are used in copper plating baths to level the
deposit across the substrate surface and to improve the throwing
power of the electroplating bath. Throwing power is defined as the
ratio of the through-hole center copper deposit thickness to its
thickness at the surface. Newer PCBs are being manufactured that
contain both through-holes and blind vias. Current bath additives,
in particular current leveling agents, do not always provide level
copper deposits between the substrate surface and filled
through-holes and blind vias. Via fill is characterized by the
difference in height between the copper in the filled via and the
surface. Accordingly, there remains a need in the art for leveling
agents for use in metal electroplating baths for the manufacture of
PCBs that provide level copper deposits while bolstering the
throwing power of the bath.
SUMMARY OF THE INVENTION
A compound including a reaction product of an amine and a quinone
where the amine has a formula:
##STR00001## where R' is selected from hydrogen or a moiety:
--CH.sub.2--CH.sub.2--; R is selected from
H.sub.2N--(CH.sub.2).sub.m--, HO--(CH.sub.2).sub.m--,
--HN--CH.sub.2--CH.sub.2--, Q-(CH.sub.2).sub.m--, a moiety having a
structure:
##STR00002## a moiety having a structure:
##STR00003## or a moiety having a structure:
##STR00004## where R.sub.1-R.sub.14 are independently chosen from
hydrogen and (C.sub.1-C.sub.3)alkyl; m is an integer from 2-12, n
is an integer from 2-10, p is an integer from 1-10, q is an integer
from 2-10 and r, s and t are numbers from 1 to 10; Q is a 5-6
membered heterocyclic ring having one or two nitrogen atoms in the
ring or Q is a benzene sulfonamide moiety; and with a proviso that
when R' is --CH.sub.2--CH.sub.2--, R is --HN--CH.sub.2--CH.sub.2--
and the nitrogen of R forms a covalent bond with a carbon atom of
R' to form a heterocyclic ring.
An electroplating bath including one or more sources of copper
ions, one or more accelerators, one or more suppressors, one or
more electrolytes and one or more compounds comprising the reaction
products disclosed above.
A method of electroplating includes providing a substrate;
immersing the substrate in the electroplating bath disclosed above;
applying a current to the substrate and the electroplating bath;
and electroplating copper on the substrate.
The reaction products provide copper layers having a substantially
level surface across a substrate, even on substrates having small
features and on substrates having a variety of feature sizes. The
electroplating methods effectively deposit copper on substrates and
in blind vias and through-holes such that the copper plating baths
have high throwing power. In addition, the copper deposits have
reduced nodules.
DETAILED DESCRIPTION OF THE INVENTION
As used throughout this specification the following abbreviations
shall have the following meanings unless the context clearly
indicates otherwise: A=amperes; A/dm.sup.2=amperes per square
decimeter; .degree. C.=degrees Centigrade; g=gram; ppm=parts per
million=mg/L; L=liter, .mu.m=micron=micrometer; mm=millimeters;
cm=centimeters; DI=deionized; mL=milliliter; mol=moles;
mmol=millimoles; Mw=weight average molecular weight; Mn=number
average molecular weight;
##STR00005## PCB=printed circuit board. All numerical ranges are
inclusive and combinable in any order, except where it is clear
that such numerical ranges are constrained to add up to 100%.
As used throughout the specification, "feature" refers to the
geometries on a substrate. "Aperture" refers to recessed features
including through-holes and blind vias. As used throughout this
specification, the term "plating" refers to electroplating.
"Deposition" and "plating" are used interchangeably throughout this
specification. "Leveler" refers to an organic compound or salt
thereof that is capable of providing a substantially level or
planar metal layer. The terms "leveler" and "leveling agent" are
used interchangeably throughout this specification. "Accelerator"
refers to an organic additive that increases the plating rate of
the electroplating bath. "Suppressor" refers to an organic additive
that suppresses the plating rate of a metal during electroplating.
The terms "printed circuit boards" and "printed wiring boards" are
used interchangeably throughout this specification. The term
"moiety" means a part of a molecule or polymer that may include
either whole functional groups or parts of functional groups as
substructures. The terms "moiety" and "group" are used
interchangeably throughout the specification. The articles "a" and
"an" refer to the singular and the plural.
Compounds include reaction products of amines and quinones as
Michael addition receptors. Amines of the present invention have
the following formula:
##STR00006## where R' is selected from hydrogen or a moiety
--CH.sub.2--CH.sub.2--; R is selected from moieties
H.sub.2N--(CH.sub.2).sub.m--, HO--(CH.sub.2).sub.m--,
--HN--CH.sub.2--CH.sub.2--, Q-(CH.sub.2).sub.m--, a moiety having a
structure:
##STR00007## a moiety having a structure:
##STR00008## or a moiety having a structure:
##STR00009## where R.sub.1-R.sub.14 are independently chosen from
hydrogen and (C.sub.1-C.sub.3)alkyl, preferably R.sub.1-R.sub.6 are
independently chosen from hydrogen and methyl, more preferably
R.sub.1-R.sub.6 are chosen from hydrogen; preferably
R.sub.7-R.sub.14 are independently chosen from hydrogen and methyl;
m is an integer from 2-12, preferably from 2-3, n is an integer
from 2-10, preferably 2-5, p is an integer from 1-10, preferably
1-5, more preferably from 1-4, q is an integer from 2-10 and r, s
and t are independently numbers from 1 to 10; Q is a 5-6 membered
heterocyclic ring having one or two nitrogen atoms in the ring such
as an imidazole or pyridine moiety, or Q is a benzene sulfonamide
moiety having formula (V) below; and with a proviso that when R' is
--CH.sub.2--CH.sub.2--, R is --HN--CH.sub.2--CH.sub.2-- and the
nitrogen of R forms a covalent bond with a carbon of R' to form a
heterocyclic ring such as a piperizine ring. Most preferably R' is
hydrogen and R is moiety (II).
##STR00010##
Amines having formula (I) include, but are not limited to ethylene
diamine, aminoethan-1-ol, 2,2'-(ethylenedioxy)bis(ethylamine),
3,3'-(butane-1,4-dihylbis(oxy))bis(propan-1-amine),
poly(l-(2-((3-(2-aminopropoxy)butan-2-yl)oxy)ethoxy)propan-2-amine)
and 4-(2-aminoethyl)benzene sulfonamide.
When n is 2 and p is 5 a preferred compound having moiety (II) is
6,8,11,15,17-pentamethyl-4,7,10,13,16,19-hexaoxadocosane-2,21-diamine
which has the following structure:
##STR00011##
A preferred compound having moiety (IV) has the following
structure:
##STR00012## where the variables r, s and t are defined above.
Preferably the Mw ranges from 200 g/mole to 2000 g/mole.
Preferably quinones include compounds having formula:
##STR00013## where R.sub.15, R.sub.16, R.sub.17 and R.sub.18 are
independently chosen from hydrogen, hydroxyl, linear or branched
hydroxy(C.sub.1-C.sub.10)alkyl halogen, linear or branched
(C.sub.1-C.sub.10)alkyl and linear or branched
amino(C.sub.1-C.sub.10)alkyl, where carbon atoms of R.sub.15 and
R.sub.16 may be taken together to form a fused aromatic ring to
form a structure having formula:
##STR00014## where R.sub.19 and R.sub.20 are the same as R.sub.17
and R.sub.18 described above and R.sub.21, R.sub.22, R.sub.23 and
R.sub.24 are independently chosen from hydrogen, hydroxyl, linear
or branched hydroxy(C.sub.1-C.sub.10)alkyl halogen, linear or
branched (C.sub.1-C.sub.10)alkyl and linear or branched
amino(C.sub.1-C.sub.10)alkyl. Preferably the quinone is formula
(VI) where R.sub.15, R.sub.16, R.sub.17 and R.sub.18 are
independently chosen from hydrogen, hydroxyl and linear or branched
(C.sub.1-C.sub.5) or formula (VII) where R.sub.19, R.sub.20,
R.sub.21, R.sub.22, R.sub.23 and R.sub.24 are independently chosen
from hydrogen, hydroxyl and linear or branched
(C.sub.1-C.sub.5)alkyl. More preferably the quinone is chosen from
formula (VI) where R.sub.15, R.sub.16, R.sub.17 and R.sub.18 are
independently chosen from hydrogen and hydroxyl and formula (VII)
where R.sub.19, R.sub.20, R.sub.21, R.sub.22, R.sub.23 and R.sub.24
are independently chosen from hydrogen and hydroxyl. A preferred
quinone having formula (VI) is benzoquinone and a preferred quinone
having formula (VII) is naphthalene-1,4-dione.
The reaction products of the present invention may be prepared by
Michael addition. Conventional Michael addition procedures may be
followed to prepare the reaction products of the present invention.
Amines function as Michael addition donors and quinones are Michael
addition acceptors. In general sufficient amount of quinone is
added to a reaction vessel followed by adding sufficient amount of
solvent such as ethanol, dichloromethane, ethyl acetate, acetone,
water or mixtures thereof. A sufficient amount of amine is then
added to the reaction vessel. Typically the molar ratio of the
amount of quinone to amine in the reaction vessel is 0.75-1:1;
however, this ratio may vary depending on the specific reactants.
Minor experimentation may be done to find the preferred reactant
molar ratios for particular reactants. The reaction may be done at
room temperature to 110.degree. C. or such as from room temperature
to 60.degree. C. for 20-24 hours or 4-6 hours.
The plating baths and methods which include one or more of the
reaction products are useful in providing a substantially level
plated metal layer on a substrate, such as a printed circuit board
or semiconductor chip. Also, the plating baths and methods are
useful in filling apertures in a substrate with metal. The copper
deposits have good throwing power and reduced nodule formation.
Any substrate upon which copper can be electroplated may be used as
a substrate with the copper plating baths containing the reaction
products. Such substrates include, but are not limited to: printed
wiring boards, integrated circuits, semiconductor packages, lead
frames and interconnects. An integrated circuit substrate may be a
wafer used in a dual damascene manufacturing process. Such
substrates typically contain a number of features, particularly
apertures, having a variety of sizes. Through-holes in a PCB may
have a variety of diameters, such as from 50 .mu.m to 350 .mu.m in
diameter. Such through-holes may vary in depth, such as from 0.8 mm
to 10 mm. PCBs may contain blind vias having a wide variety of
sizes, such as up to 200 .mu.m diameter and 150 .mu.m depth, or
greater.
The copper plating baths contain a source of copper ions, an
electrolyte, and a leveling agent, where the leveling agent is a
reaction product of one or more amines and one or more acrylamides
as described above. The copper plating baths may contain a source
of halide ions, an accelerator and a suppressor. Optionally, in
addition to copper, the electroplating baths may include one or
more sources of tin for electroplating a copper/tin alloy.
Preferably the electroplating baths are copper electroplating
baths.
Suitable copper ion sources are copper salts and include without
limitation: copper sulfate; copper halides such as copper chloride;
copper acetate; copper nitrate; copper tetrafluoroborate; copper
alkylsulfonates; copper aryl sulfonates; copper sulfamate; copper
perchlorate and copper gluconate. Exemplary copper alkane
sulfonates include copper (C.sub.1-C.sub.6)alkane sulfonate and
more preferably copper (C.sub.1-C.sub.3)alkane sulfonate. Preferred
copper alkane sulfonates are copper methanesulfonate, copper
ethanesulfonate and copper propanesulfonate. Exemplary copper
arylsulfonates include, without limitation, copper benzenesulfonate
and copper p-toluenesulfonate. Mixtures of copper ion sources may
be used. One or more salts of metal ions other than copper ions may
be added to the present electroplating baths. Typically, the copper
salt is present in an amount sufficient to provide an amount of
copper metal of 10 to 400 g/L of plating solution.
Suitable tin compounds include, but are not limited to salts, such
as tin halides, tin sulfates, tin alkane sulfonate such as tin
methane sulfonate, tin aryl sulfonate such as tin benzenesulfonate
and tin p-toluenesulfonate. The amount of tin compound in these
electrolyte compositions is typically an amount that provides a tin
content in the range of 5 to 150 g/L. Mixtures of tin compounds may
be used in an amount as described above.
The electrolyte useful in the present invention is acidic.
Preferably, the pH of the electrolyte is .ltoreq.2. Suitable acidic
electrolytes include, but are not limited to, sulfuric acid, acetic
acid, fluoroboric acid, alkanesulfonic acids such as
methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and
trifluoromethane sulfonic acid, aryl sulfonic acids such as
benzenesulfonic acid, p-toluenesulfonic acid, sulfamic acid,
hydrochloric acid, hydrobromic acid, perchloric acid, nitric acid,
chromic acid and phosphoric acid. Mixtures of acids may be
advantageously used in the present metal plating baths. Preferred
acids include sulfuric acid, methanesulfonic acid, ethanesulfonic
acid, propanesulfonic acid, hydrochloric acid and mixtures thereof.
The acids may be present in an amount in the range of 1 to 400 g/L.
Electrolytes are generally commercially available from a variety of
sources and may be used without further purification.
Such electrolytes may optionally contain a source of halide ions.
Typically chloride ions are used. Exemplary chloride ion sources
include copper chloride, tin chloride, sodium chloride, potassium
chloride and hydrochloric acid. A wide range of halide ion
concentrations may be used in the present invention. Typically, the
halide ion concentration is in the range of 0 to 100 ppm based on
the plating bath. Such halide ion sources are generally
commercially available and may be used without further
purification.
The plating compositions typically contain an accelerator. Any
accelerators (also referred to as brightening agents) are suitable
for use in the present invention. Such accelerators are well-known
to those skilled in the art. Accelerators include, but are not
limited to, N,N-dimethyl-dithiocarbamic acid-(3-sulfopropyl)ester;
3-mercapto-propylsulfonic acid-(3-sulfopropyl)ester;
3-mercapto-propylsulfonic acid sodium salt; carbonic acid,
dithio-O-ethylester-S-ester with 3-mercapto-1-propane sulfonic acid
potassium salt; bis-sulfopropyl disulfide; bis-(sodium
sulfopropyl)-disulfide; 3-(benzothiazolyl-S-thio)propyl sulfonic
acid sodium salt; pyridinium propyl sulfobetaine;
1-sodium-3-mercaptopropane-1-sulfonate; N,N-dimethyl-dithiocarbamic
acid-(3-sulfoethyl)ester; 3-mercapto-ethyl propylsulfonic
acid-(3-sulfoethyl)ester; 3-mercapto-ethylsulfonic acid sodium
salt; carbonic acid-dithio-O-ethylester-S-ester with
3-mercapto-1-ethane sulfonic acid potassium salt; bis-sulfoethyl
disulfide; 3-(benzothiazolyl-S-thio)ethyl sulfonic acid sodium
salt; pyridinium ethyl sulfobetaine; and
1-sodium-3-mercaptoethane-1-sulfonate. Accelerators may be used in
a variety of amounts. In general, accelerators are used in an
amount in a range of 0.1 ppm to 1000 ppm.
Any compound capable of suppressing the metal plating rate may be
used as a suppressor in the present electroplating compositions.
Suitable suppressors include, but are not limited to, polypropylene
glycol copolymers and polyethylene glycol copolymers, including
ethylene oxide-propylene oxide ("EO/PO") copolymers and butyl
alcohol-ethylene oxide-propylene oxide copolymers. Suitable butyl
alcohol-ethylene oxide-propylene oxide copolymers are those having
a weight average molecular weight of 100 to 100,000 g/mole,
preferably 500 to 10,000 g/mole. When such suppressors are used,
they are typically present in an amount in the range of 1 to 10,000
ppm based on the weight of the composition, and more typically from
5 to 10,000 ppm. The leveling agents of the present invention may
also possess functionality capable of acting as suppressors.
In general, the reaction products have a number average molecular
weight (Mn) of 200 to 100,000 g/mole, typically from 300 to 50,000
g/mole, preferably from 500 to 30,000 g/mole, although reaction
products having other Mn values may be used. Such reaction products
may have a weight average molecular weight (Mw) value in the range
of 1000 to 50,000 g/mole, typically from 5000 to 30,000 g/mole,
although other Mw values may be used.
The amount of the reaction product, i.e., leveling agent, used in
the electroplating baths depends upon the particular leveling
agents selected, the concentration of the metal ions in the
electroplating bath, the particular electrolyte used, the
concentration of the electrolyte and the current density applied.
In general, the total amount of the leveling agent in the
electroplating baths ranges from 0.01 ppm to 1000 ppm, preferably
from 0.1 ppm to 100 ppm, most preferably from 0.5 ppm to 50 ppm,
based on the total weight of the plating bath, although greater or
lesser amounts may be used.
The electroplating baths may be prepared by combining the
components in any order. It is preferred that the inorganic
components such as source of metal ions, water, electrolyte and
optional halide ion source are first added to the bath vessel,
followed by the organic components such as leveling agent,
accelerator, suppressor, and any other organic component.
The electroplating baths may optionally contain at least one
additional leveling agent. Such additional leveling agents may be
another leveling agent of the present invention, or alternatively,
may be any conventional leveling agent. Suitable conventional
leveling agents that can be used in combination with the present
leveling agents include, without limitations, those disclosed in
U.S. Pat. No. 6,610,192 to Step et al., U.S. Pat. No. 7,128,822 to
Wang et al., U.S. Pat. No. 7,374,652 to Hayashi et al. and U.S.
Pat. No. 6,800,188 to Hagiwara et al. Such combination of leveling
agents may be used to tailor the characteristics of the plating
bath, including leveling ability and throwing power.
Typically, the plating baths may be used at any temperature from 10
to 65.degree. C. or higher. Preferably, the temperature of the
plating bath is from 10 to 35.degree. C. and more preferably from
15 to 30.degree. C.
In general, the electroplating baths are agitated during use. Any
suitable agitation method may be used and such methods are
well-known in the art. Suitable agitation methods include, but are
not limited to: air sparging, work piece agitation, and
impingement.
Typically, a substrate is electroplated by contacting the substrate
with the plating bath. The substrate typically functions as the
cathode. The plating bath contains an anode, which may be soluble
or insoluble. Potential is typically applied to the electrodes.
Sufficient current density is applied and plating performed for a
period of time sufficient to deposit a metal layer having a desired
thickness on the substrate as well as to fill blind vias, trenches
and through-holes, or to conformally plate through-holes. Current
densities may range from 0.05 to 10 A/dm.sup.2, although higher and
lower current densities may be used. The specific current density
depends in part upon the substrate to be plated, the composition of
the plating bath, and the desired surface metal thickness. Such
current density choice is within the abilities of those skilled in
the art.
An advantage of the present invention is that substantially level
metal deposits are obtained on a PCB. Through-holes, blind vias or
combinations thereof in the PCB are substantially filled or
through-holes are conformally plated with desirable throwing power.
A further advantage of the present invention is that a wide range
of apertures and aperture sizes may be filled or conformally plated
with desirable throwing power.
Throwing power is defined as the ratio of the average thickness of
the metal plated in the center of a through-hole compared to the
average thickness of the metal plated at the surface of the PCB
sample and is reported as a percentage. The higher the throwing
power, the better the plating bath is able to conformally plate the
through-hole. Metal plating compositions of the present invention
have a throwing power of .gtoreq.45%, preferably .gtoreq.50%.
The reaction products provide copper and copper/tin layers having a
substantially level surface across a substrate, even on substrates
having small features and on substrates having a variety of feature
sizes. The plating methods effectively deposit metals in
through-holes such that the electroplating baths have good throwing
power.
While the methods of the present invention have been generally
described with reference to printed circuit board manufacture, it
is appreciated that the present invention may be useful in any
electrolytic process where an essentially level or planar copper or
copper/tin deposit and filled or conformally plated apertures are
desired. Such processes include semiconductor packaging and
interconnect manufacture.
The following examples are intended to further illustrate the
invention but are not intended to limit its scope.
Example 1
22.5 mmol benzoquinone is added into a 100 mL three necked flask
followed by 30 mL mixture of ethanol and water. Then 30 mmol
2,2'-(ethylenedioxy)bis(ethylamine) is added into the reaction
mixture. The reaction is done at room temperature overnight. After
the reaction is complete, all the solvent is removed under reduced
pressure a solid material. Reaction product 1 is used without
purification.
Example 2
22.5 mmol benzoquinone is added into a 100 mL three necked flask
followed by 30 mL mixture of ethanol and water. Then 30 mmol
6,8,11,15,17-pentamethyl-4,7,10,13,16,19-hexaoxadocosane-2,21-diamine
is added into the reaction mixture. The reaction is done at room
temperature. The reaction mixture is kept overnight at room
temperature. All the solvent is removed under reduced pressure
leaving a solid material. Reaction product 2 is used without
purification.
Example 3
22.5 mmol naphthalene-1,4-dione is added into a 100 mL three necked
flask followed by 30 mL mixture of ethanol and water. Then 30 mmol
6,8,11,15,17-pentamethyl-4,7,10,13,16,19-hexaoxadocosane-2,21-diamine
is added into the reaction mixture. The reaction is done at
110.degree. C. over 4-5 hours. All the solvent is removed under
reduced pressure leaving a solid material. Reaction product 3 is
used without purification.
Example 4
A plurality of copper electroplating baths are prepared by
combining 75 g/L copper as copper sulfate pentahydrate, 240 g/L
sulfuric acid, 60 ppm chloride ion, 1 ppm of an accelerator and 1.5
g/L of a suppressor. The accelerator is
bis(sodium-sulfopropyl)disulfide. The suppressor is an EO/PO
copolymer having a weight average molecular weight of <5,000 and
terminal hydroxyl groups. Each electroplating bath also contains
one of reaction products 1-3 in amounts from 2 ppm to 20 ppm as
shown in the table in Example 5 below. The reaction products are
used without purification.
Example 5
Samples of 3.2 mm thick, double-sided FR4 PCBs, 5 cm.times.9.5 cm,
having a plurality of through-holes are electroplated with copper
in Haring cells using the copper electroplating baths of Example 4.
The samples have 0.25 mm diameter through-holes. The temperature of
each bath is 25.degree. C. A current density of 3 A/dm.sup.2 is
applied to the samples for 40 minutes. The copper plated samples
are analyzed to determine the throwing power ("TP") of the plating
baths, and the number of nodules on the copper deposits.
Throwing power is calculated by determining the ratio of the
average thickness of the copper plated in the center of a
through-hole compared to the average thickness of the copper plated
at the surface of the PCB sample. The throwing power is reported in
the table as a percentage.
TABLE-US-00001 Reaction Product Leveler (ppm) % TP Nodules 1 2 60 0
5 57 0 10 50 0 2 5 57 0 10 53 0 20 54 1 3 2 71 0 5 63 0 10 54 0
The results show that the throwing power exceeds 45% indicating
good throwing power performance for the reaction products. In
addition, all of the samples show significant nodule reduction on
the copper deposits.
* * * * *